1. Field of the Invention
This invention relates to a white balance control system, and more particularly to a system for easy and accurate control of the white balance of the video signal of color television cameras.
2. Description of the Prior Art
In color television cameras.Iadd., .Iaddend.the white balance is lost generally by changes in color temperature of illumination for an object to be televised, or by secular change of video amplifiers or other components of the image pickup tube due to variations in temperature or the like. It is the practice in the prior art while televising a white object.Iadd., .Iaddend.to control the gains of gain control circuits provided in all or in two of the amplifiers for the red, green and blue video signals in a manner to retain the signals at substantially the same level. However, control of each color exerts a influence upon the balance of the other two colors, so that accurate adjustment of the white balance is difficult and the operation .[.therefor.]. .Iadd.therefore .Iaddend.is troublesome.